The overall objective of this proposal is to continue the support at Vanderbilt University of an existing interdepartmental, multidisciplinary Population Research Center. The continuous support of the Center will maintain the efficiency of many population related projects now active at Vanderbilt and will permit development in new areas not presently represented. The research objectives of the Center include investigations on male reproductive physiology (sperm production, sperm biochemistry, sperm metabolism, sperm maturation, sperm capacitation, development of male contraception, and neuroendocrine control of male sexual behavior), on female reproductive physiology (fertilization and implantation), on reproductive endocrinology (reproductive hormones structure, synthesis, metabolism, and mechanism of action), and on reproductive pathology (gonococcal-induced female infertility and malignant transformation of the human mammary gland). Support is requested for an administrative core unit and eight core facilities (Histology & Photomicroscopy, Electron Microscopy, Tissue Culture, Cyclic Nucleotide, Prostaglandin, Hormone Assay, Organic Chemistry, Monoclonal Antibody).